Original Norman Rockwell paintings created after 1942, contain one or more features Mr. Rockwell employed to prevent forgery. In 2006 it was discovered that an impostor of Norman Rockwell's 1954 painting, ‘Breaking Home Ties’ was on exhibit at the Norman Rockwell Museum. Authentication may have avoided this error.
The 1930's saw rapid technological advancements in the field of photography and the standardization of color models by the International Commission on Illumination (CIE). In 1938, Mr. Martin J. Weber, created a variety of innovative methods for photography and filed a patent application for a process called, “Posterization.” Mr. Weber's invention caused two-dimensional photographs to appear as three-dimensional images that sprung off the page. Posterization, a type of color quantization, is a highly technical process which uses a fixed palette (RGB or CMYK) and then minimizes the number of colors used within the same color model. A photograph is converted into a series of three negatives, each designated for a different color. When the three negatives are printed or otherwise presented together, each slightly off-register, the final product appears to be three-dimensional.
Around 1940, Mr. Rockwell realized that some of the innovations of the 1930s might also be applicable to painted artwork and began blending Posterization and Steganography, the art of hiding data in a cover medium, to provide anti-forgery features to his paintings. Mr. Rockwell used RGB model paints to hide his initials and the syllables of his name in the CMYK paint colors he used. The human eye does not perceive the slight difference between the CMYK colors and RGB colors and any variation in shade between the two types of paint does not appear on a photograph taken with a camera since cameras operate on the RGB color model.